The Army has released photos of unique underground training operations undertaken by troops in a little-known Texas nuclear bunker.

The Cold War era bunker was created after the World War II when engineers blasted a series of tunnels into a mountain at West Fort Hood, according to the U.S. Army.

Originally called "Project 76" by what was then the War Department, construction actually began on the bunker in 1947 when miners were brought in to start work without being given any idea what the tunnels would be for.

Located on what was then called Killeen Base, the bunker ended up being the only atomic weapons storage facility operated by the Army, eventually being decommissioned in the 1960s and more recently converted for training operations.

"We went in to raid the tunnel complex," Pfc. Dwight Donahue, a SAW gunner for 1st Platoon, Ironhawk Troop told the Fort Hood Sentinel. "It was crazy and much better than going to a range. It was dark and loud. Moving around in there with the grenade simulators echoing off the walls and the 249 firing was very intense."

Training operations in the bunker simulate tunnel raids. Soldiers face an enemy group inside the underground chambers, which are 20 feet wide with 30 foot ceilings and penetrate to a depth of 80 plus feet below the mountain top.

The Army says conducting training like this forces troops to learn to pay much closer attention to detail.

"There is power in this type of training," Capt. Kyle Stockwell, commander of Ironhawk Troop said in the Sentinel release. "This is directly replicated in theater."

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